BEIJING –North Korea declared Saturday it has entered "a state of war" with South Korea in the latest of a string of threats that have raised tensions on the Korean Peninsula.

North Korea's government, parties and organizations said in a joint statement that all matters between the two countries will now be dealt with in a manner befitting war

The Korean Peninsula is already in a technical state of war because the Korean War ended in a cease-fire, not a peace treaty. But Pyongyang ditched that armistice earlier this month.

South Korea's Unification Ministry quickly released a statement calling the latest threat not new and saying it is a follow-up to Kim's earlier order to put troops on a high alert in response to annual U.S-South Korean defense drills. Pyongyang sees those drills as rehearsals for an invasion.

Earlier, North Korean dictator Kim Jong Un, lashing out at America's "reckless provocations," readied his rocket forces to "to settle accounts with the U.S." a day after U.S. massive B-2 bombers roared into the area for a bombing drill with U.S. ally South Korea.

Kim ordered the country's strategic rocket units placed on standby to hit the U.S. mainland and U.S. military bases in the latest response by Pyongyang to the imposition of new international sanctions over it for its third nuclear test. The test was a violation of international agreements signed by the North.

North Korean forces should "mercilessly strike" the United States and its military bases in the Pacific, including Hawaii, Guam and in South Korea, said Kim, according to the state-run Korean Central News Agency. Kim signed the order at an overnight meeting Thursday night, said the agency.

Some military experts doubt North Korea is capable of achieving such strikes but it could target South Korean territory and ships as it has done in recent years, but worried that the North could launch an attack close by that would prompt a retaliation from the U.S,. military, which vowed this week to depend its Asia ally.

"I don't think military action will be imminent," said Lim Eul-chul, a professor of North Korean studies at Kyungnam University in Seoul.

Despite the bellicose statements, "Kim Jong Un wants to terminate the repeated harsh action and reaction [cycle] with the United States. They want to establish a more eternal peace mechanism and they want a more sustainable relationship with the USA."

The United States has said if the North wants a better relationship it must cease the threats, its nuclear program and development of long-range missiles. North Korea has refused to take part in negotiations over its weapons programs, and it refuses to abide by its obligations under treaties to open up its nuclear facilities to inspection.

At the main square Friday in Pyongyang, tens of thousands of North Koreans turned out for a 90-minute mass rally in support of Kim's call to arms. Men and women, many in uniforms, stood in straight lines, fists raised and chanting, "Death to the U.S. imperialists." Placards in the plaza aimed at the South Koreans said, "Let's rip the puppet traitors to death!"

The Rodong Sinmun newspaper, the main mouthpiece of the North's communist regime, published photographs Friday of Kim and his generals with a chart marked "U.S. Mainland Strike Plan," showing routes for envisioned strikes against cities on both American coasts. The map bore the title "U.S. Mainland Strike Plan."

Portions of the photo appeared to be manipulated, and the Pentagon has said it does not believe the North can launch a nuclear-armed missile at the continental United States. But it could fire some of its inventory of tens of thousands of rockets at the South Korean capital of Seoul, or at Japan.

According to the state-run North Korean Central News agency, Kim said "the time has come to settle accounts with the U.S. imperialists in view of the prevailing situation,"

North Korean warships conducted maritime drills off both coasts of North Korea near the border with South Korea on Thursday, South Korean Defense Ministry spokesman Kim Min-seok said Friday. He said South Korea's military was mindful of the possibility that North Korean drills could lead to an actual provocation.

U.S. Forces Korea, which oversees about 30,000 American troops stationed in the country, said the B-2 stealth bombers flew from a U.S. air base in Missouri and dropped dummy munitions on a South Korean island bombing range on Thursday. The flights were part of annual military drills conducted by U.S.-Korean forces.

The United States says it has no intention of attacking the North, but the Kim family dynasty, now in its third generation of complete power over the North Korean people for nearly six decades, severely restricts outside information from getting into the country and runs extensive propaganda campaigns to persuade the nation to live in fear of U.S. attack.

South Korea needs to lead the process, says Lim, such as making moves to negotiate a peace agreement that Washington will support, he said.

"Without negotiations, North Korea will continually step up military tensions on the peninsula," Lim said.

But in past negotiations with U.S. presidents North Korea failed to abide by its written promises to curtail its nuclear and missile program in return for foreign aid, food, and energy technology. In 2010, North Korea sank the South Korean naval corvette Cheonan south of the maritime boundary, killing 46 sailors. That year it attacked Yeonpyeong Island with artillery, killing four South Koreans and destroying 70 homes and buildings.

South Korean President Park Geun Hye has said her government will not tolerate any military attacks from the North, which has a long history of launching assaults against previous governments in the South. Park has said she wants to re-engage North Korea, stressing the need for greater trust, but Pyongyang will "pay the price" for any provocation.

The North had to react to the appearance of B-2 bombers over South Korea, "but I don't think they are ready to go to war," said Tong Kim, an international relations expert at Korea University. "It's a really dangerous cycle of heightening tensions."

But the continuing operation of the Kaesong industrial zone, where South Korean employees cross daily into the North to work, "is a really good sign that North Korea is not ready to go to war at this moment," he said.

The zone also employs as many as 50,000 North Koreans and is perhaps the only true commercial activity taking place in what some call the "Hermit Kingdom."

Pyongyang needs some "face-saving rationale to calm down", without disappointing its own people, said Tong.

The United States has appealed for China, the North's only significant ally, to convince it to calm down and negotiate its future. U.S. policy for North Korea is to facilitate a change in the regime and the peaceful reunification of the nation split in two since the 1950s.

The Chinese Communist party has taken little action on the matter. Wang Dong, an academic at government-funded Peking University in Beijing, say the United States bears some responsibility for the situation.

North Korea become a nuclear power, "to negotiate from a position of strength," but the United States will not agree to the negotiations Pyongyang seeks, he said. President Obama stonewalled the "basketball diplomacy" effort that Kim tried with former NBA star Dennis Rodman, who recently visited Pyongyang, said Wang.

Beijing faces a difficult situation, he said.

"Many people believe that as long as China puts enough pressure on North Korea, the regime will collapse, and everything will be fine, but that's simplistic thinking," he said. "A collapse or a war scenario would be hugely costly. We need to respond in a very responsible and cautious way."

Meanwhile, in a typical piece in Rodong Sinmun, the newspaper reported that, "The whole country is bubbling like a melting pot. We can no more endure. Open fire at the enemies' stronghold! … Reduce Washington to ashes with a preemptive precision nuclear strike!"

North Korea, which has missiles capable of hitting U.S. territories in the Pacific and possibly mainland USA, has ordered its rocket and long-range artillery units to be combat ready after joint military drills by U.S. and South Korean forces. A look at the Koreas and the military presence and threat: